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.Dd October 1, 2008
.Dt PTHREAD_SETUGID_NP 2
.Os
.Sh NAME
.Nm pthread_setugid_np
.Nd Set the per-thread userid and single groupid.
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/unistd.h>
.Ft int
.Fn pthread_setugid_np "uid_t uid, gid_t gid"
.Sh DESCRIPTION
.Fn pthread_setugid_np
changes the current thread's effective, real, and saved userid and groupid to the requested
userid and groupid (
.Fa uid
and
.Fa gid
, respectively) and clears all other groupids.
.Pp
.Fa uid
can be the current real userid, KAUTH_UID_NONE, or, if the caller is privileged, any userid.
.Fa gid
can be the current real groupid or, if the caller is priviledged, any single groupid.
.Pp
Setting
.Fa uid 
to KAUTH_UID_NONE means to "revert to the per process credential".
.Sh CAVEATS
Temporarily restoring root privileges for a non-privileged process is only possible on a per-process basis and not a per-thread basis.
.Pp
.Fn pthread_setugid_np 
is not intended as a privilege escalation mechanism.
.Pp
Do not use
.Fn pthread_setugid_np.2
in a security sensitive situation.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, -1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn pthread_setugid_np
fails if one or more of the following are true:
.\" ========
.Bl -tag -width Er
.It Bq EPERM
The calling process does not have the correct credentials to set the override identity (i.e. The current credentials do not imply "super-user").
.\" ========
.It Bq EPERM
If
.Fa uid
is set to KAUTH_UID_NONE, 
the current thread must already be assuming another identity in order to revert back.
.\" ========
.It Bq EPERM
The current thread cannot already be assuming another identity.
.El
.Sh SEE ALSO
.Xr setuid 2
.Xr setgid 2
.Xr seteuid 2
.Xr setegid 2
